I am running Bitcoin with the -datadir= thing to keep all my files under Truecrypt.And I want to back them up on my DropBox account. That i encrypt with Truecrypt. So it would be 2 layers of Truecrypt and any Encryption Dropbox uses.Would this work?

(I am a 1MB block supporter who thinks all users should be using Full-Node clients)Avoid the XT shills, they only want to destroy bitcoin, their hubris and greed will destroy us.Know your adversary https://www.youtube.com/watch?v=BKorP55Aqvg

The block chain is the main innovation of Bitcoin. It is the
first distributed timestamping system.

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The principle is that a TrueCrypt volume is created within another TrueCrypt volume (within the free space on the volume). Even when the outer volume is mounted, it should be impossible to prove whether there is a hidden volume within it or not*, because free space on any TrueCrypt volume is always filled with random data when the volume is created** and no part of the (dismounted) hidden volume can be distinguished from random data.

As myrkul states, "...PIE (Pre Internet Encryption) is the way to go..."

Translation. Encrypt your things before you store them online. That way you will be safe (assuming you have a strong password/pass phrase)., if that site is ever breached (from a hacker and/or rouge employee).

Also as myrkul points out. Dropbox's encryption should not be solely relied upon (well he didn't say that, however that is what I took out of it ). It they are breached, Dropbox has the keys for their encryption.

Think about it. It they are hacked, the hackers will take the data and the keys.